using System;

using System.Collections.Generic;

using System.IO;

​

interface IMessage

{

    void Visit(IMessageVisitor v);

    void Deserialize(BinaryReader r);

}

​

struct Message1 : IMessage

{

    public void Visit(IMessageVisitor v) { v.Visit(ref this); }

    public void Deserialize(BinaryReader r) { Float = r.ReadSingle(); }

    public float Float;

}

​

struct Message2 : IMessage

{

    public void Visit(IMessageVisitor v) { v.Visit(ref this); }

    public void Deserialize(BinaryReader r) { UInt = r.ReadUInt32(); }

    public uint UInt;

}

​

​

​

interface IMessageVisitor

{

    void Visit(ref Message1 m);

    void Visit(ref Message2 m);

}

​

class MessagePrinter : IMessageVisitor

{

    public void Visit(ref Message1 m) { Console.WriteLine("Message1: {0}", m.Float); }

    public void Visit(ref Message2 m) { Console.WriteLine("Message2: {0:x}", m.UInt); }

}

​

​

​

class MessageQueue

{

    readonly Queue<uint> Queue = new Queue<uint>(); // index of next SubQueue

    readonly IMessageSubQueue[] SubQueue = new IMessageSubQueue[] {

        // index = uint32ified type

        new MessageSubQueue<Message1>(),

        new MessageSubQueue<Message2>(),

    };

​

    public int Count => Queue.Count;

​

    public void QueueDeserialize(BinaryReader reader)

    {

        var count = reader.ReadUInt32();

        for (uint i = 0; i < count; ++i)

        {

            var type = reader.ReadUInt32();

            SubQueue[type].QueueDeserialize(reader);

            Queue.Enqueue(type);

        }

    }

​

    public void Dequeue(IMessageVisitor v)

    {

        var type = Queue.Dequeue();

        SubQueue[type].Dequeue(v);

    }

​

    interface IMessageSubQueue

    {

        void QueueDeserialize(BinaryReader reader);

        void Dequeue(IMessageVisitor v);

    }

​

    class MessageSubQueue<M> : IMessageSubQueue where M : IMessage, new()

    {

        readonly Queue<M> Queue = new Queue<M>();

​

        public void QueueDeserialize(BinaryReader reader)

        {

            var m = new M();

            m.Deserialize(reader);

            Queue.Enqueue(m);

        }

​

        public void Dequeue(IMessageVisitor v)

        {

            Queue.Dequeue().Visit(v);

        }

    }

}

​

​

​

class Program {

    static void Main(string[] args) {

        var queue = new MessageQueue();

        queue.QueueDeserialize(new BinaryReader(new MemoryStream(new byte[] {

            3, 0, 0, 0,                         // 3 messages

            1, 0, 0, 0, 1, 2, 3, 4,             // Message2 { Uint = 0x04030201 }

            0, 0, 0, 0, 0xDB, 0x0F, 0x49, 0x40, // Message1 { Float = pi }

            1, 0, 0, 0, 4, 3, 2, 1,             // Message2 { Uint = 0x01020304 }

        })));

​

        var printer = new MessagePrinter();

        while (queue.Count > 0)

        {

            queue.Dequeue(printer);

        }

    }

}

​